Nearly everything in nature has a distinctive scent that can be identified with the sense of smell. In this essay I will address what the smell molecules are, how humans can smell them, and how some smell molecules can be created, such as perfumes. I will also address two different forms of extraction of smell molecules from rose petals in my section about my experiments.
Smell molecules are volatized aqueous hydrocarbons. There are countless different shapes and combinations that these molecules can take on, all of which have different smells. Scientists haven't figured out why different shapes have different smells, or how to determine a smell by the compound of a molecule.5 An interesting discovery is how the smell molecules change as they rot.2 Amines form aggregates with the molecules, and since all amines are different, they have different effects on the smell molecule. Some amines will make the molecule tighter, while others make the molecules more spaced out. As the molecules change, their smell will change. The changes they undergo eventually change the scent put off by the molecules a bad odor.
Humans can smell all of these compounds through nerves in the nose.4 The nerves are submerged in a layer of mucus, but besides this thin layer of mucus, the nerves are unprotected from the outer world. Every single other nerve in the body has skin protecting it from nature, so smell is the most powerful way of sensing things in humans. The nerves in the nose connect directly to the brain. Another interesting fact is that the part of the brain the nerves in the nose connect to is right next to the part that controls instinctual emotions, which scientists suspect is why certain smells can cause such strong emotions in humans.5
The way that the nerves sense the molecules in the air is that the molecules dissolve into the mucus that covers the nerves. That is why humans can only smell aqueous compounds, because they have to dissolve into the liquid mucus to be sensed. The sense of smell is also similar to that of taste in the manner of detecting smells. There are 1,000 genes in the olfactory system that each sense a different type of smell, much like taste buds.4 While all the genes can sense every type of smell, each individual gene has a specific type of smell it can sense much more powerfully than any of the other genes. The information about smells that are sensed here is sent to another part of the olfactory system, called the glomerulus. Another 2,000 genes are located here which turned the signals from the receptors in the nose into a smell. The large number of genes here makes humans able to sense a vast variety of smells.
Perfumes are made by diluting smell molecules in a mixture of alcohol and water (the mixture is 2% water and 98% alcohol)4. The make-ups in the perfumes include many different types of hydrocarbons, like aldehydes, ketones, alcohols, esters and ethers. And example of a combination would be citral (C10H16O) and acetone (CO(CH3)2) form the ketone ionone, which smells like violets. All the alcohol in the mixture spreads out the smell molecules in the perfume, so that they can be distinguished. The smells in the mixture emerge like waves. For example, first a perfume smells like cherry, then apple, and then mango.
While scientists have discovered make-ups of scents and can create perfumes with them, little more is actually known. Scientists have not figured out how these carbon chains can actually cause our senses to react in the way they do to create the image of that certain scent in our brains. Similarly, they have not figured out why each specific shape of a compound smells like all other smell molecules that have the same shape. It is predicted that more will be brought into the light soon though.
Procedure
LAB EXPERIMENT
Materials
• 75 grams of Rose Petals
• 250 mL of Water (for the petals)
• 500 mL boiling flask
• 50 mL of dichloromethane or petroleum ether
• Anhydrous Magnesium sulfate
• Apparatus for the Steam Distillation
o Claisen Adapter
o Thermometer
o Condenser
o Distillation Adapter
Procedure (roughly 3 hours, prep materials at break and start at lunch, should be done a little after school ends)
• Place petals and 250 mL of water into the boiling flask
• Clamp the flask to be heated with a boiler flame and fit it with a Claisen adapter (center neck of the adapter with a separator funnel, and the side neck with a distillation adapter carrying a thermometer and a condenser set for downward distillation)
• Distill the mixture rapidly by heating the flask with a burner until nothing more forms in the condensate
• Extract the condensate from the distillate with 50 mL of dichloromethane or petroleum ether
• Isolate by drying the extract over anhydrous magnesium sulfate
• Remove the petal extract from the dichloromethane or petroleum ether by distillation on the steam bath
HOME EXPERIMENT
Materials
• Rose Petals (9 cups)
• Plates, dinner-size (4)
• Scissors
• Cardboard (1 large piece)
• Ruler
• Aluminum foil (1 roll)
• Knife or spreader
• Vegetable shortening (1 small container)
• Tablespoon
• Paper towels (1 roll)
• Table
• Books (to apply pressure, about 5 lbs)
• Watch
• Tweezers
• Measuring cup, liquid
• Ethyl alcohol (1 1/4 cup)
• Paper coffee cup
• Double boiler
• Spoon
• Jelly jars and lids, small, cleaned in a dishwasher and completely air-dried (9)
• Masking tape
• Pen
• Sketchbook paper
Performing the Experiment
1. Pluck the flower petals off a few of the flowers and put them on the plate. You should have about 1 1/2 cups of flower petals.
2. Using the scissors, cut out six pieces of cardboard that are each 4 inches x 4 inches.
3. Take a piece of aluminum foil and wrap a piece of cardboard securely with the foil so that no cardboard is showing. Neatly fold the excess foil onto one side of the cardboard. Repeat this step with the five other pieces of cardboard.
4. Spread about 1 tablespoon (tbsp.) of vegetable shortening onto one of the foil-covered cardboard squares with the knife or spreader. Do your best to spread it into a neat square that is no thicker than 1/4 inch. The square of shortening should be about 3 inches x 3 inches. If necessary, you can use more or less vegetable shortening. Repeat this step with the five other pieces of cardboard.
5. Roughly shred the flower petals with your hands if they are large. Take a 1/4 cup of petals and gently press them into the shortening on one of the cardboard pieces covered with shortening and foil. You should completely cover the shortening with the petals. Repeat this step with the rest of the cardboard pieces covered with shortening and foil.
6. Put two pieces of covered cardboard together with the layer of shortening and petals in the middle, like a sandwich. Make two more sandwiches with the other covered cardboard pieces. You should now have three sandwiches of cardboard, foil, shortening, and petals.
7. Rip off two paper towels, together, and fold them along the perforation. Put one of the sandwiches on the double sheet of paper towels and wrap the paper towel around it, flipping it over so the weight of the sandwich holds the folded-under pieces down. Repeat this step with the two additional sandwiches. You should now have three sandwiches, all for one trial.
8. Find a location in your home that is free from drafts and will not be disturbed. Place the three sandwiches on a table and then place a 5-lb. book on each of the sandwiches. Your effleurage setup is now complete. Note down the time and the date in your lab notebook.
9. How long will it take for the scent of the flowers to permeate the shortening? What will happen to the petals? This is what you will find out. Let the sandwiches sit for one day (a full 24 hours), undisturbed.
10. After one day, unwrap one of the sandwiches and gently pull apart the foil-covered cardboard pieces. What do the petals look like? Using the tweezers, pick off all of the petals from the shortening and discard them. How does the vegetable shortening smell? Note the time, the day, and all of your observations in your lab notebook. Clean the tweezers after using them.
11. Using the knife or spreader, scrape and gather the vegetable shortening into one lump. You should have about 2 tbsp. of vegetable shortening. You will need to use an equivalent amount of alcohol. Put 2 tbsp. of alcohol in the paper cup.
12. Read the instructions on how to use the double boiler, or use your homemade one. Put the appropriate amount of water into the bottom pot. If you are using a stainless steel bowl and a pot, instead of a double boiler, place some water in the bottom pot. Make sure that the water level is lower than the bottom of the bowl when it sits inside the larger pot. Place the bowl into the larger pot.
13. Place the double boiler on the stovetop burner and turn on the burner to medium. Place the shortening in the upper pot. Slowly melt the vegetable shortening. Don't let the shortening boil or burn.
14. When the vegetable shortening has completely melted, turn off the burner and add the ethyl alcohol to the shortening. Mix the alcohol and the vegetable shortening together well with the spoon. Allow the mixture to cool slightly.
15. Once the mixture has cooled, pour it into a jelly jar and put the lid on. Using your masking tape and pen, write on the side of the jelly jar the trial and the days of effleurage. Put the jar in a dark spot and let it sit for 1 full week. Discard the empty foil, but keep the cardboard pieces.
16. As soon as you have finished processing the first sandwich, obtain more flowers and remove the petals. Roughly shred the petals if they are large. You should have 1 cup of petals for this step.
17. Unwrap the second sandwich and gently pull apart the foil-covered cardboard pieces. Using the tweezers, remove the petals from the vegetable shortening and discard them. Take a 1/4 cup of fresh petals and press them gently into the vegetable shortening of one of the foil-covered cardboard pieces. Take another 1/4 cup of fresh petals and gently press them into the vegetable shortening of the other foil-covered cardboard piece. Put the sandwich back together and rewrap it in the paper towel. Replace the sandwich under the book.
18. Repeat this step with the third sandwich and the extra 1/2 cup of petals.
19. After another day (24 hours), obtain more flowers and remove the petals. Roughly shred the petals if they are large. You should have a 1/2 cup of petals for this step.
20. Unwrap the second sandwich and repeat steps 10–15.
21. Unwrap the third sandwich and repeat step 16
22. After one more day, unwrap the third sandwich and repeat steps 10-15
Results
Experiment #1
The process took a lot shorter than the predicted time, and a few minor changes had to made since the original experiment had been for extracting peanut oil from peanuts, though the changes were simple and easy to deal with. A very small amount of scent molecules were extracted from from this experiment (but they really reeked). While the smell of a stereotypical rose was apparent, the smell of boiling cabbages was strongly apparent throughout the experiment. There was no estimated amount at the beginning of the experiment so I don't have a percent error, though I think that I lost a little between all the switching of the rose oil between containers.
Experiment #2
A long experiment, as the longer the time the oil spent in fresh roses, the more it soaked up (and smelled). At the end, This smelled better than the first... but it wasn't a pure extract and would require more steps to get the oil from the roses into a pure scent extract
Conclusions
#1
The solution that I had created in this experiment was small and strong, and in a very early state, many additions and changes had to be made before it could be turned into a perfume. If I wanted to get a sizable amount from this experiment, I need to start with a lot more roses. There also is probably a much easier and more effect way to extract the scent of roses from the petals.
#2
This experiment doesn't get far enough into the steps to be worth anything in the long run. While an easier home experiment, the first is the way to go if you want an actual rose extract.
The Chemistry Of Smell
MarcusIntroduction
Nearly everything in nature has a distinctive scent that can be identified with the sense of smell. In this essay I will address what the smell molecules are, how humans can smell them, and how some smell molecules can be created, such as perfumes. I will also address two different forms of extraction of smell molecules from rose petals in my section about my experiments.
Smell molecules are volatized aqueous hydrocarbons. There are countless different shapes and combinations that these molecules can take on, all of which have different smells. Scientists haven't figured out why different shapes have different smells, or how to determine a smell by the compound of a molecule.5 An interesting discovery is how the smell molecules change as they rot.2 Amines form aggregates with the molecules, and since all amines are different, they have different effects on the smell molecule. Some amines will make the molecule tighter, while others make the molecules more spaced out. As the molecules change, their smell will change. The changes they undergo eventually change the scent put off by the molecules a bad odor.
Humans can smell all of these compounds through nerves in the nose.4 The nerves are submerged in a layer of mucus, but besides this thin layer of mucus, the nerves are unprotected from the outer world. Every single other nerve in the body has skin protecting it from nature, so smell is the most powerful way of sensing things in humans. The nerves in the nose connect directly to the brain. Another interesting fact is that the part of the brain the nerves in the nose connect to is right next to the part that controls instinctual emotions, which scientists suspect is why certain smells can cause such strong emotions in humans.5
The way that the nerves sense the molecules in the air is that the molecules dissolve into the mucus that covers the nerves. That is why humans can only smell aqueous compounds, because they have to dissolve into the liquid mucus to be sensed. The sense of smell is also similar to that of taste in the manner of detecting smells. There are 1,000 genes in the olfactory system that each sense a different type of smell, much like taste buds.4 While all the genes can sense every type of smell, each individual gene has a specific type of smell it can sense much more powerfully than any of the other genes. The information about smells that are sensed here is sent to another part of the olfactory system, called the glomerulus. Another 2,000 genes are located here which turned the signals from the receptors in the nose into a smell. The large number of genes here makes humans able to sense a vast variety of smells.
Perfumes are made by diluting smell molecules in a mixture of alcohol and water (the mixture is 2% water and 98% alcohol)4. The make-ups in the perfumes include many different types of hydrocarbons, like aldehydes, ketones, alcohols, esters and ethers. And example of a combination would be citral (C10H16O) and acetone (CO(CH3)2) form the ketone ionone, which smells like violets. All the alcohol in the mixture spreads out the smell molecules in the perfume, so that they can be distinguished. The smells in the mixture emerge like waves. For example, first a perfume smells like cherry, then apple, and then mango.
While scientists have discovered make-ups of scents and can create perfumes with them, little more is actually known. Scientists have not figured out how these carbon chains can actually cause our senses to react in the way they do to create the image of that certain scent in our brains. Similarly, they have not figured out why each specific shape of a compound smells like all other smell molecules that have the same shape. It is predicted that more will be brought into the light soon though.
Procedure
LAB EXPERIMENT
Materials
• 75 grams of Rose Petals
• 250 mL of Water (for the petals)
• 500 mL boiling flask
• 50 mL of dichloromethane or petroleum ether
• Anhydrous Magnesium sulfate
• Apparatus for the Steam Distillation
o Claisen Adapter
o Thermometer
o Condenser
o Distillation Adapter
Procedure (roughly 3 hours, prep materials at break and start at lunch, should be done a little after school ends)
• Place petals and 250 mL of water into the boiling flask
• Clamp the flask to be heated with a boiler flame and fit it with a Claisen adapter (center neck of the adapter with a separator funnel, and the side neck with a distillation adapter carrying a thermometer and a condenser set for downward distillation)
• Distill the mixture rapidly by heating the flask with a burner until nothing more forms in the condensate
• Extract the condensate from the distillate with 50 mL of dichloromethane or petroleum ether
• Isolate by drying the extract over anhydrous magnesium sulfate
• Remove the petal extract from the dichloromethane or petroleum ether by distillation on the steam bath
HOME EXPERIMENT
Materials
• Rose Petals (9 cups)
• Plates, dinner-size (4)
• Scissors
• Cardboard (1 large piece)
• Ruler
• Aluminum foil (1 roll)
• Knife or spreader
• Vegetable shortening (1 small container)
• Tablespoon
• Paper towels (1 roll)
• Table
• Books (to apply pressure, about 5 lbs)
• Watch
• Tweezers
• Measuring cup, liquid
• Ethyl alcohol (1 1/4 cup)
• Paper coffee cup
• Double boiler
• Spoon
• Jelly jars and lids, small, cleaned in a dishwasher and completely air-dried (9)
• Masking tape
• Pen
• Sketchbook paper
Performing the Experiment
1. Pluck the flower petals off a few of the flowers and put them on the plate. You should have about 1 1/2 cups of flower petals.
2. Using the scissors, cut out six pieces of cardboard that are each 4 inches x 4 inches.
3. Take a piece of aluminum foil and wrap a piece of cardboard securely with the foil so that no cardboard is showing. Neatly fold the excess foil onto one side of the cardboard. Repeat this step with the five other pieces of cardboard.
4. Spread about 1 tablespoon (tbsp.) of vegetable shortening onto one of the foil-covered cardboard squares with the knife or spreader. Do your best to spread it into a neat square that is no thicker than 1/4 inch. The square of shortening should be about 3 inches x 3 inches. If necessary, you can use more or less vegetable shortening. Repeat this step with the five other pieces of cardboard.
5. Roughly shred the flower petals with your hands if they are large. Take a 1/4 cup of petals and gently press them into the shortening on one of the cardboard pieces covered with shortening and foil. You should completely cover the shortening with the petals. Repeat this step with the rest of the cardboard pieces covered with shortening and foil.
6. Put two pieces of covered cardboard together with the layer of shortening and petals in the middle, like a sandwich. Make two more sandwiches with the other covered cardboard pieces. You should now have three sandwiches of cardboard, foil, shortening, and petals.
7. Rip off two paper towels, together, and fold them along the perforation. Put one of the sandwiches on the double sheet of paper towels and wrap the paper towel around it, flipping it over so the weight of the sandwich holds the folded-under pieces down. Repeat this step with the two additional sandwiches. You should now have three sandwiches, all for one trial.
8. Find a location in your home that is free from drafts and will not be disturbed. Place the three sandwiches on a table and then place a 5-lb. book on each of the sandwiches. Your effleurage setup is now complete. Note down the time and the date in your lab notebook.
9. How long will it take for the scent of the flowers to permeate the shortening? What will happen to the petals? This is what you will find out. Let the sandwiches sit for one day (a full 24 hours), undisturbed.
10. After one day, unwrap one of the sandwiches and gently pull apart the foil-covered cardboard pieces. What do the petals look like? Using the tweezers, pick off all of the petals from the shortening and discard them. How does the vegetable shortening smell? Note the time, the day, and all of your observations in your lab notebook. Clean the tweezers after using them.
11. Using the knife or spreader, scrape and gather the vegetable shortening into one lump. You should have about 2 tbsp. of vegetable shortening. You will need to use an equivalent amount of alcohol. Put 2 tbsp. of alcohol in the paper cup.
12. Read the instructions on how to use the double boiler, or use your homemade one. Put the appropriate amount of water into the bottom pot. If you are using a stainless steel bowl and a pot, instead of a double boiler, place some water in the bottom pot. Make sure that the water level is lower than the bottom of the bowl when it sits inside the larger pot. Place the bowl into the larger pot.
13. Place the double boiler on the stovetop burner and turn on the burner to medium. Place the shortening in the upper pot. Slowly melt the vegetable shortening. Don't let the shortening boil or burn.
14. When the vegetable shortening has completely melted, turn off the burner and add the ethyl alcohol to the shortening. Mix the alcohol and the vegetable shortening together well with the spoon. Allow the mixture to cool slightly.
15. Once the mixture has cooled, pour it into a jelly jar and put the lid on. Using your masking tape and pen, write on the side of the jelly jar the trial and the days of effleurage. Put the jar in a dark spot and let it sit for 1 full week. Discard the empty foil, but keep the cardboard pieces.
16. As soon as you have finished processing the first sandwich, obtain more flowers and remove the petals. Roughly shred the petals if they are large. You should have 1 cup of petals for this step.
17. Unwrap the second sandwich and gently pull apart the foil-covered cardboard pieces. Using the tweezers, remove the petals from the vegetable shortening and discard them. Take a 1/4 cup of fresh petals and press them gently into the vegetable shortening of one of the foil-covered cardboard pieces. Take another 1/4 cup of fresh petals and gently press them into the vegetable shortening of the other foil-covered cardboard piece. Put the sandwich back together and rewrap it in the paper towel. Replace the sandwich under the book.
18. Repeat this step with the third sandwich and the extra 1/2 cup of petals.
19. After another day (24 hours), obtain more flowers and remove the petals. Roughly shred the petals if they are large. You should have a 1/2 cup of petals for this step.
20. Unwrap the second sandwich and repeat steps 10–15.
21. Unwrap the third sandwich and repeat step 16
22. After one more day, unwrap the third sandwich and repeat steps 10-15
Results
Experiment #1
The process took a lot shorter than the predicted time, and a few minor changes had to made since the original experiment had been for extracting peanut oil from peanuts, though the changes were simple and easy to deal with. A very small amount of scent molecules were extracted from from this experiment (but they really reeked). While the smell of a stereotypical rose was apparent, the smell of boiling cabbages was strongly apparent throughout the experiment. There was no estimated amount at the beginning of the experiment so I don't have a percent error, though I think that I lost a little between all the switching of the rose oil between containers.
Experiment #2
A long experiment, as the longer the time the oil spent in fresh roses, the more it soaked up (and smelled). At the end, This smelled better than the first... but it wasn't a pure extract and would require more steps to get the oil from the roses into a pure scent extract
Conclusions
#1
The solution that I had created in this experiment was small and strong, and in a very early state, many additions and changes had to be made before it could be turned into a perfume. If I wanted to get a sizable amount from this experiment, I need to start with a lot more roses. There also is probably a much easier and more effect way to extract the scent of roses from the petals.
#2
This experiment doesn't get far enough into the steps to be worth anything in the long run. While an easier home experiment, the first is the way to go if you want an actual rose extract.
References
Dowdey, Sarah. "HowStuffWorks "Detection of Odorants"" Howstuffworks "Health" Web. 03 May 2010. <http://health.howstuffworks.com/smell1.htm>.
Finke, Aaron. "Carbon-Based Curiosities » Blog Archive » Because Organic Chemistry Doesn’t Smell Bad Enough." Carbon-based Kittiosities!!!!!!11oenone. June 2009. Web. 03 May 2010. .
Ikenberry, Esther. "Perfume and Chemistry." JSTOR. Dec. 1951. Web. 03 May 2010. .Nasr, Susan L. "HowStuffWorks "What Is Perfume?"" Howstuffworks "Science" Web. 03 May 2010. <http://science.howstuffworks.com/perfume1.htm>.